Created attachment 8435040[details][review]
Pull request 19886
Pulling patch out of bug 1019058 into a dedicated bug:
> Here is another patch, more complex, but this one comes with more than just
> performances benefit. It would help revive about:gaia addon by simplifying
> the Makefile and easing building gaia from just JS script.
>
> Before and ffter executing build script/Makefile per app, we execute a bunch
> of js script from build/. Before: svoperapps, webapp-manifest,
> contact-import-services, keyboard-layouts, settings, webapp-shared. After:
> post-manifest, copy-build-stage-data, webapp-optimize, multilocale,
> webapp-zip. The key thing here is that there is some small overhead in
> executing xpcshell many times.
>
> With the previous patch applied and this new one, for APP=clock make, It
> lower down build time from 4.3s to 3.0s (-30%).
>
> I just asked for feedback as I haven't had time to test/verify this patch.
>
> A natural followup of this patch would be to implement app-makefiles in JS
> and merge pre-app app-makefiles and post-app into a single one, but that
> would require getting rid of all app-specific Makefiles. The gain should be
> even more significant for complete build as we are running one xpcshell
> instance per app.

Comment on attachment 8435040[details][review]
Pull request 19886
I tested it with PRODUCTION, MOZILLA_OFFICIAL, some other parameter and on Windows and all looks good!
BTW, I found a bug when I was testing on windows on bug 1021578